What fields can I check?

You can see the version, serial number, signature algorithm, issuer, subject, validity period, public key algorithm and bit length, SAN, and SHA-256 fingerprint.

Does it tell me whether the certificate has expired?

It shows the validity start and expiry dates, so you can compare them against the current date yourself to check for expiry.

Is the certificate I enter sent to a server?

No. ASN.1 DER parsing is performed entirely in your browser.

🔍 SSL Certificate Viewer

Paste a PEM-format (-----BEGIN CERTIFICATE-----) SSL certificate to see its details.

Certificate PEM

How to use

Paste a PEM-format SSL certificate.
Click "Check".
Details like issuer, validity period, public key, and SAN are displayed.

🎯 Use Cases

Check the expiry date of a certificate installed on a server
Check the issuer in a certificate chain
Check coverage via the SAN (alternate domain) list

Example

Input

-----BEGIN CERTIFICATE-----
MIIF...(example.com leaf certificate PEM, truncated)...aQ==
-----END CERTIFICATE-----

Output

Version: v3
Signature Algorithm: ecdsa-with-SHA256
Issuer: C=US, O=SSL Corporation, CN=Cloudflare TLS Issuing ECC CA 3
Subject: CN=example.com
Public Key Algorithm: id-ecPublicKey (256 bit)
SAN (Alternate Names): example.com, *.example.com

An illustrative result shown when pasting the example.com certificate PEM. Issuer, subject, public key, and SAN differ for every real certificate, so this is a representative sample.

FAQ

What fields can I check?: You can see the version, serial number, signature algorithm, issuer, subject, validity period, public key algorithm and bit length, SAN, and SHA-256 fingerprint.
Does it tell me whether the certificate has expired?: It shows the validity start and expiry dates, so you can compare them against the current date yourself to check for expiry.
Is the certificate I enter sent to a server?: No. ASN.1 DER parsing is performed entirely in your browser.